Heterogeneous catalysts are used under increasingly harsh conditions, requiring the use of high-performance ceramics with high thermal and chemical stability as carrier material. In addition, a high surface area for an effective reaction at the active sites and well-tailored macroporous structures for high product flow are required. Currently, conventional ceramic processes are highly limited in meeting these shaping requirements, which calls for additive manufacturing in the form of stereolithography. Polymer-derived ceramics exhibit outstanding thermal properties and allow for a direct introduction of metal centres into the ceramic matrix through chemical modification, rendering them ideal candidate materials for catalysis applications. This study investigates the fabrication of complex lattice structures via stereolithography of polysiloxane and further thermal conversion into SiOC ceramics. Two approaches to modifying the photoactive polysiloxane printing system were developed.
On the one hand, the addition of SiC particles to the printing resin significantly increased the stability of the specimens and the freedom of design during the process. This combination allowed the production of defect-free, dense SiOC/SiC composite material with a characteristic strength of 325 MPa obtained with a biaxial ball-on-three-balls testing methodology. Secondly, chemical modification of the base material was carried out using metalorganic compounds to create metal-ceramic hybrid materials. Thus, nanoscale nickel particles could be generated in-situ during the polymer-to-ceramic conversion. In combination with the modification via the nickel complexes, phase separation phenomena were observed, which led to the formation of micelles in the printing system. This separation subsequently led to the generation of hierarchical porosity, in addition to the printed macrostructure. The synergies of both approaches are used to produce stable ceramic catalyst support materials containing a catalytically active phase. By selecting the process parameters during the production of the printing resin, the printing process and the pyrolytic conversion, phase development and microstructural evolution of the metallic phases as well as the generation of the porosity, were elucidated. Furthermore, the influence of these parameters on the catalytic activity of the produced materials regarding CO2 methanation was determined.